Type-specific persistence and associated risk factors of human papillomavirus infections in women living in central Italy.

OBJECTIVE: We examined persistence and clearance of human papillomavirus (HPV) infections and risk factors associated with persistence in 79 women based on the results of two sequential tests performed over 12-24 months. STUDY
DESIGN: Between February 2008 and August 2009, 398 women aged 18-63 years were examined for presence of cervical HPV infection by cervical scrape specimen and PCR. Detection was performed using Linear Array (LA) HPV Genotyping Test. All women were interviewed, and a short questionnaire was administered to collect information on socio-demographic characteristics, sexual and reproductive history, smoking habits, oral contraceptive use, history of sexually transmitted diseases, and Chlamydia trachomatis or Mycoplasma spp. infections. Pearson's χ² test was used to verify the association between all independent variables with the response variable.
RESULTS: Initially, high risk-HPV (HR-HPV) and low risk-HPV (LR-HPV) infection was detected in 69.6% and 30.4% of the women, respectively, whilst multiple infections occurred in 53.2%. HPV 16 was the most common (20.2%) high-risk type, followed by 52, 31 and 53. At follow-up, HR-HPV infection was detected in 50.6% of the women; among these, 67.5% had persistent infection, while 12.5% acquired other high-risk types, and 20.0% of those positive for LR-HPV at entry had a new HR-HPV infection. Multiple infections were detected in 38.0% of the women. HPV 16 and 31 were the most frequent types, followed by HPV 73. Type-specific HR-HPV persistence was found in 49.1% of women. HPV 31, 39 and 73 were the most frequently persistent types, whilst HPV 16 was the least persistent. No significant age difference between women with persistence or clearance was found. The highest HR-HPV persistence occurred in the 22-27 years old group, whereas clearance increased in women aged 28-33 years. No significant association between persistent HR-HPV infection and oral contraceptive use, smoking habits and history of sexually transmitted disease was detected both at entry and follow-up study. The association between C. trachomatis or Mycoplasma spp. and HPV persistence could not be investigated because of the low detection rate of these microorganisms.
CONCLUSIONS: The persistence of HR-HPV infection level was similar to that reported elsewhere, and HPV 31, 39 and 73 showed the highest likelihood of persistence, partially in agreement with other studies. The clinical relevance of the low persistence of HPV 16 and other HR-HPV is unknown. Persistent HR-HPV infection in women aged 22-27 years was in agreement with other authors. To the best of our knowledge, this is the first report on persistence of HR-HPV infections in Italy in a general population, although we examined a small sample in a short follow-up time.